1. Field of the Invention
The present invention relates to disk cartridges and more specifically to a disk cartridge which rotatably accommodates a disk-like recording medium such as a magnetic disk, a CD-ROM, an MOD, etc., and which issued in a drive apparatus.
2. Description of the Background Art
A conventional disk cartridge is disclosed, for example in Japanese Patent Publication No. 4-42754 (hereinafter "conventional art 1"), for example. In the conventional art 1, a case is constructed from an upper half and a lower half. The case is formed in a rectangular shape with a notch portion at a corner of an end of an inserting direction and head insert holes on each of the upper half and the lower half. A U-shaped shutter (or a channel shaped showing a sectional shape of steel) is openably formed to cover the head insert holes, and a disk-like recording medium is accommodated in the case. In use, the disk cartridge of the conventional art 1 is horizontally inserted in a drive apparatus to be loaded by going downward to a thickness direction (a vertical direction) when it is completely inserted. The shutter is normally biased to a closed position by a spring. Then, when the disk cartridge of the conventional art 1 is loaded in the drive apparatus, the shutter is opened while the disk cartridge is being horizontally inserted. When the disk cartridge is completely inserted, the notch portion at the end of the inserting direction can distinguish whether the insertion is reversed or not to ensure normal loading. After the loading is completed, heads inside the drive apparatus cross a cartridge front edge portion (a shutter front edge portion) being opened upward and downward and approach the disk in a position corresponding to the head insert holes.
Another disk cartridge is disclosed in Japanese Patent Publication No. 4-66078 (hereinafter "conventional art 2"). In the conventional art 2, an edge surface portion of a shutter corresponding to a head insert hole when the shutter is opened is formed to be narrow in width so as to be thinner than other portions.
Since the disk cartridge of the conventional art 1 is inserted so that an upper head and a lower head on the drive apparatus interpose the disk-like recording medium from above and below from the head insert holes of the upper half and the lower half, respectively, when the disk cartridge is loaded in the drive apparatus, a space between the upper head and the lower head has to be large, which makes it difficult to make the drive apparatus thin. Also, since stroke of an up/down motion of the heads becomes large, the disk cartridge has a disadvantage that the precision of the head positioning is reduced by the up/down motion. Specifically, the head positioning accuracy has a large influence when the medium accommodated in the case is capable of high-density recording. Furthermore, it is impossible to detect whether the insertion is in a normal direction or in a reverse direction until the disk is almost completely inserted in the drive apparatus, which may cause damage to the apparatus by pushing the disk without knowing of the reverse insertion.
On the other hand, the conventional art 2 is much the same as the conventional art 1 in the point that the disk cartridge is inserted so that an upper head and a lower head interpose a disk-like recording medium from above and below from head insert holes of an upper half and a lower half, respectively. The difference is just that an upper head stroke and a lower head stroke can be slightly smaller than the conventional art 1.
Moreover, both in the conventional art 1 and the conventional art 2, since the head insert holes are formed on both sides of the upper half and the lower half, a problem rises that the case easily breaks down because of a low strength of the case. As a result, when the case receives an outer stress, for example, when the cartridge case is stepped on or wrenched, the disk-like recording medium and maybe scratched, damaging recorded data.